Measure the insulation resistance of capacitors,the following points should be noted:
(1) A 500 or 1000 volt megohmmeter can be used to measure low-voltage capacitors, and a 2500 volt megohmmeter should be used to measure high-voltage capacitors.
(2) The capacitor should be discharged before and after the shaking test to avoid electric shock accidents.
(3) When measuring, first set the megger to the specified speed (120 rpm), wait for its pointer to stabilize, then connect the megger wire to the two poles of the capacitor, and then continue to rotate the megger. At the beginning, as the capacitor is charged, the pointer of the meter will drop, and then slowly rise until it stabilizes. At this time, the reading on the megohmmeter is the insulation resistance between the capacitors.
(4) Since the capacitor is composed of series and parallel capacitor components, the insulation deterioration of individual components will not significantly reduce the insulation resistance of the entire capacitor. Therefore, it is generally difficult to find defects in the insulation resistance between electrodes. Therefore, the relevant regulations are only The test item for testing the insulation resistance of the two poles to the enclosure is specified, but the insulation resistance value is not specified. According to operating experience, the insulation resistance value of the two poles to the shell should generally be greater than 2000 megohms during the handover test, and not less than 1000 megohms during the preventive test.measure the insulation resistance of capacitors